CN114070042B - Three-level resonant DCDC converter and voltage equalizing control method - Google Patents

Three-level resonant DCDC converter and voltage equalizing control method Download PDF

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Publication number
CN114070042B
CN114070042B CN202010784670.2A CN202010784670A CN114070042B CN 114070042 B CN114070042 B CN 114070042B CN 202010784670 A CN202010784670 A CN 202010784670A CN 114070042 B CN114070042 B CN 114070042B
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voltage
capacitor
switching tube
duty ratio
duty cycle
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CN114070042A (en
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占金祥
王均
林天散
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Huawei Digital Power Technologies Co Ltd
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Huawei Digital Power Technologies Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
    • H02M3/07—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider using capacitors charged and discharged alternately by semiconductor devices with control electrode, e.g. charge pumps
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/083—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the ignition at the zero crossing of the voltage or the current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The application provides a three-level resonance DCDC converter and a voltage equalizing control method, which comprises the following steps: the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the first capacitor, the second capacitor, the fifth switch module and the sixth switch module are connected in series with the input end of the DCDC converter; the controller adjusts the duty ratio of the first switching tube and the duty ratio of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, so that the first voltage and the second voltage are equal. And when the first voltage is larger than the second voltage, the duty ratio of the fourth switching tube is reduced to increase the second voltage of the second capacitor. When the first voltage is smaller than the second capacitor, the duty ratio of the first switch tube is reduced to reduce the second voltage of the second capacitor. The duty ratio is adjusted to control the charge and discharge of the capacitor, so that the voltage on the capacitor is adjusted, the voltage equalizing of the first capacitor and the second capacitor is realized, and a new hardware circuit is not needed to be added.

Description

Three-level resonant DCDC converter and voltage equalizing control method
Technical Field
The application relates to the technical field of power electronics, in particular to a three-level resonant DCDC converter and a voltage equalizing control method.
Background
The resonant DCDC converter is a direct current conversion circuit in which an output voltage and an input voltage have a fixed voltage ratio. The resonant DCDC converter can realize soft switching of all switching tubes by controlling the switching frequency of the switching tubes, and reduces the overall switching loss, thereby improving the working efficiency of the resonant DCDC converter.
Currently, the two-level resonant DCDC converter is widely applied, as shown in fig. 1, and is a topology diagram of the two-level resonant DCDC converter in the prior art.
Where Vin is the input voltage and Vo is the output voltage. When the first switching tube T1 is closed and the second switching tube T2 is opened, the resonance inductance Lr and the resonance capacitance Cr are charged. When the first switching tube T1 is opened and the second switching tube T2 is closed, the resonance inductor Lr and the resonance capacitor Cr discharge the capacitor C2, so that energy of the input end is transferred to the output end.
For application to higher voltage levels, multilevel resonant converters have evolved. Compared with the traditional two-level resonant converter, the multi-level resonant converter realizes multi-level by improving the topological structure of the multi-level resonant converter, and further realizes medium-voltage high-power output. Under the same input condition, the multi-level resonant converter has the outstanding advantages that the voltage stress of power devices such as a switch tube can be reduced, and therefore, higher-level voltage output can be realized by using power devices with smaller withstand voltage level. Therefore, the multi-level resonant converter has wide application prospect in the medium-voltage high-power occasion.
However, in the multilevel resonant DCDC converter, the input terminal includes a plurality of capacitors connected in series, and when there is a deviation in the capacitance value of the capacitors, a problem of uneven voltage occurs.
Disclosure of Invention
In order to solve the technical problems, the application provides a three-level resonant DCDC converter and a voltage equalizing control method, which can realize voltage equalizing of all capacitors at the input end of the three-level resonant DCDC converter.
The embodiment of the application provides a three-level resonant DCDC converter, which comprises the following components: the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the first capacitor, the second capacitor, the fifth switching module and the sixth switching module form a three-level DCDC circuit, and the first capacitor and the second capacitor are connected in series at the input end of the three-level resonant DCDC converter; further comprises: the device comprises a resonance capacitor, a resonance inductor, a first diode, a second diode, a third capacitor and a controller; the third capacitor is connected in parallel between the positive output end and the negative output end of the three-level resonant DCDC converter; the first diode and the second diode are connected in series and then connected in parallel to two ends of the third capacitor; the first end of the resonance capacitor and the resonance inductor which are connected in series is connected with the common end of the second switching tube and the common end of the third switching tube, and the second end of the resonance capacitor and the resonance inductor which are connected in series is connected with the common end of the first diode and the second diode; the controller is used for adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor so that the first voltage and the second voltage are consistent.
The fifth switch module and the sixth switch module can be diodes, and can also be controllable switch tubes, such as IGBT or MOS, and the controllable switch tubes can be controlled to realize the functions of the diodes.
And according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube to make the first voltage and the second voltage equal. For example, when the first voltage is greater than the second voltage, the duty cycle of the fourth switching tube is reduced to increase the second voltage of the second capacitor. And when the first voltage is smaller than the second capacitor, reducing the duty ratio of the first switching tube to reduce the second voltage of the second capacitor. Namely, the duty ratio of T1 and T4 is adjusted to control the charge and discharge of C1 and C2, so that the voltages of C1 and C2 are adjusted, and the voltage equalizing of C1 and C2 is realized. According to the scheme, a new hardware circuit is not required to be added, and voltage sharing can be realized by the controller through control.
Preferably, the controller is specifically configured to decrease the duty cycle of the fourth switching tube to increase the second voltage of the second capacitor when the first voltage is greater than the second voltage.
Preferably, the controller is specifically configured to obtain a difference between the first voltage and the second voltage when the first voltage is greater than the second voltage, and reduce a duty cycle of the fourth switching tube according to the difference, so as to increase the second voltage of the second capacitor; the duty ratio variation of the fourth switching tube is positively correlated with the difference value.
Preferably, the controller is specifically configured to reduce the duty cycle of the first switching tube when the first voltage is smaller than the second capacitance, so as to reduce the second voltage of the second capacitance.
Preferably, the controller is specifically configured to obtain a difference between the first voltage and the second voltage when the first voltage is smaller than the second voltage, and reduce a duty cycle of the first switching tube according to the difference so as to reduce the second voltage of the second capacitor; the duty ratio variation of the first switching tube is positively correlated with the difference value.
Preferably, the controller is specifically configured to obtain a difference value between the first voltage and the second voltage, perform proportional integral adjustment or proportional integral differential adjustment on the difference value, obtain a duty cycle variation, respectively superimpose the variation on a duty cycle of the first switching tube and a duty cycle of the second switching tube, perform amplitude limiting on the varied duty cycle of the first switching tube, output the amplitude limited duty cycle of the first switching tube to the first switching tube, and perform amplitude limiting on the varied duty cycle of the fourth switching tube, and output the amplitude limited duty cycle of the fourth switching tube to the fourth switching tube.
Preferably, the fifth switch module is a fifth diode, and a cathode of the fifth diode is connected with a common end of the first switch tube and the second switch tube; the anode of the fifth diode is connected with the common end of the first capacitor and the second capacitor;
The sixth switch module is a sixth diode, the cathode of the sixth diode is connected with the anode of the fifth diode, and the anode of the sixth diode is connected with the common ends of the third switch tube and the fourth switch tube.
Based on the three-level resonant DCDC converter provided by the application, the application also provides a voltage equalizing control method based on the DCDC converter, namely, the method is applied to the converter and comprises the following steps:
Obtaining a first voltage of the first capacitor and a second voltage of the second capacitor;
and according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, adjusting the duty ratio of the first switch and the duty ratio of the fourth switch tube to enable the first voltage and the second voltage to be consistent.
Preferably, according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, the duty ratio of the first switch and the duty ratio of the fourth switch tube are adjusted, which specifically includes:
When the first voltage is larger than the second voltage, obtaining a difference value between the first voltage and the second voltage, and reducing the duty ratio of the fourth switching tube according to the difference value so as to increase the second voltage of the second capacitor; the duty ratio variation of the fourth switching tube is positively correlated with the difference value.
Preferably, according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, the duty ratio of the first switch and the duty ratio of the fourth switch tube are adjusted, which specifically includes:
When the first voltage is smaller than the second voltage, a difference value between the first voltage and the second voltage is obtained, and the duty ratio of the first switching tube is reduced according to the difference value so as to reduce the second voltage of the second capacitor; the duty ratio variation of the first switching tube is positively correlated with the difference value.
The embodiment of the application also provides a photovoltaic system, which comprises the DCDC converter and an inverter, wherein the input end of the DCDC converter is connected with the photovoltaic array, and the output end of the DCDC converter is connected with the inverter. Wherein the photovoltaic array may comprise a plurality of strings of photovoltaic groups, for example comprising a plurality of strings of photovoltaic groups connected together in parallel.
Compared with the prior art, the scheme provided by the application has the following advantages:
And according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube to make the first voltage and the second voltage equal. For example, when the first voltage is greater than the second voltage, the duty cycle of the fourth switching tube is reduced to increase the second voltage of the second capacitor. And when the first voltage is smaller than the second capacitor, reducing the duty ratio of the first switching tube to reduce the second voltage of the second capacitor. Namely, the duty ratio of T1 and T4 is adjusted to control the charge and discharge of C1 and C2, so that the voltages of C1 and C2 are adjusted, and the voltage equalizing of C1 and C2 is realized. According to the scheme, a new hardware circuit is not required to be added, and voltage sharing can be realized by the controller through control.
Drawings
FIG. 1 is a topology diagram of a two-level resonant DCDC converter according to the prior art;
Fig. 2 is a topology diagram of a three-level resonant DCDC converter provided by the present application;
FIG. 3 is a topology of yet another three-level resonant DCDC converter provided by the present application;
fig. 4 is a driving timing chart of the NPC type three-level resonant DCDC converter corresponding to fig. 2;
FIG. 5 is a driving timing diagram when V1> V2;
FIG. 6 is a schematic diagram of the path when T4 is turned on;
FIG. 7 is a schematic diagram of the path when T4 is turned off;
FIG. 8 is a driving timing diagram for V1< V2;
FIG. 9 is a schematic diagram of the path when T1 is turned on;
FIG. 10 is a schematic diagram of the path when T1 is turned off;
FIG. 11 is a schematic diagram of a controller implementing control adjustment provided by the present application;
fig. 12 is a flowchart of a control method provided by the present application.
Detailed Description
Firstly, in order to make the technical scheme provided by the application better understood by the person skilled in the art, the topology and the working principle of the three-level resonant DCDC converter are described below.
Referring to fig. 2, the topology diagram of the three-level resonant DCDC converter provided by the present application is shown.
The three-level resonant DCDC converter provided in this embodiment includes: the first switching tube T1, the second switching tube T2, the third switching tube T3, the fourth switching tube T4, the first capacitor C1, the second capacitor C2, the fifth switching module and the sixth switching module form a three-level DCDC circuit. In fig. 2, the fifth switch module and the sixth switch module are each exemplified by diodes, for example, as shown in fig. 2, D5 and D6, respectively.
The negative end of the fifth diode D5 is connected with the common end of the first switching tube T1 and the second switching tube T2; the positive end of the fifth diode D5 is connected with the common end of the first capacitor C1 and the second capacitor C2;
the negative terminal of the sixth diode D6 is connected to the positive terminal of the fifth diode D5, and the positive terminal of the sixth diode D6 is connected to the common terminal of the third switching tube T3 and the fourth switching tube T4.
The first capacitor C1 and the second capacitor C2 are connected in series with the input end of the three-level resonance DCDC converter; further comprises: resonance capacitor Cr, resonance inductance Lr, first diode D7, second diode D8, and third capacitor C3; i.e. C1 and C2 are connected in series between the positive input and the negative input, wherein C1 is close to the positive input and C2 is close to the negative input, i.e. the voltage after C1 and C2 are connected in series is the input voltage, i.e. the input bus voltage. T1, T2, T3 and T4 are connected in series in sequence and then connected in parallel with the positive input end and the negative input end, namely a first branch formed by connecting C1 and C2 in series is connected in parallel with a second branch formed by connecting T1-T4 in series. Cr and Lr form an LC resonant circuit.
The third capacitor C3 is connected in parallel between the positive output end and the negative output end of the three-level resonant DCDC converter; the first diode D7 and the second diode D8 are connected in series and then connected in parallel to two ends of the third capacitor C3; the voltage on C3 is the output voltage.
The first end of the resonance capacitor Cr and the resonance inductor Lr after being connected in series is connected with the common end of the T2 and the T3, and the second end of the resonance capacitor Cr and the resonance inductor Lr after being connected in series is connected with the common end of the first diode D7 and the second diode D8.
The voltage stress of T1-T6 is half of the voltage of the input bus, so that a device with smaller withstand voltage can be selected. The input bus voltage is the voltage of two ends of C1 and C2 after being connected in series, wherein the first end of C1 is connected with the positive input end of the bus, the second end of C1 is connected with the first end of C2, and the second end of C2 is connected with the negative input end of the bus. In fig. 2, the fifth and sixth switching modules are described by taking diodes as an example. In addition, the fifth switch module and the sixth switch module can be switch tubes, namely controllable switch tubes, and the functions of the diodes can be realized through control. As shown in fig. 3, the fifth switching module is a fifth switching tube T5, and the sixth switching module is a sixth switching tube T6.
The embodiment of the application is not particularly limited to the specific implementation form of T1-T6, and can be a controllable switch device such as IGBT, MOS and the like.
The above is a specific connection structure of the three-level resonant DCDC converter, and a specific operation principle of the three-level resonant DCDC converter is described below with reference to a driving timing chart shown in fig. 4.
The transducer shown in fig. 3 comprises 8 modes of operation, which are analyzed separately as follows:
working modes 1, 2, 3:
The modes of operation 1, 2, 3 are the transitions of the resonant circuit from the negative half-cycle to the positive half-cycle. The mode 1 is turned off at the initial time T4, then T2 is turned on, and T3 is turned off. In the transient process, the resonant current is always 0, and no loss is generated.
Working mode 4:
Mode 4 starts T1 on, and C1, C2 charges the resonance capacitor Cr through T1, T2, lr, cr, D7 loops. After half a resonance period, the resonance current drops to 0, and this state will be maintained until T1 turns off, since the voltage of the resonance capacitor Cr is higher than the positive input bus voltage at this time.
Working modes 5, 6, 7:
Modes 5, 6, 7 are transitions in which the resonant circuit switches from the positive half-cycle to the negative half-cycle. T1 is turned off, T3 is turned on, and then T2 is turned off.
Working mode 8:
Mode 8 begins T4 on and resonance capacitor Cr discharges C3 through Lr, T3, T4, C3, D8. The control of the switching frequency is smaller than the resonant frequency of the resonant circuit, so that the resonant current is reduced to 0 when the T4 is turned off, and soft switching is realized.
The switching modes 1-8 realize the process that energy is transferred from an input bus to a resonant capacitor Cr and then to an output bus (two ends of C3), and as the switching tube can be controlled to realize soft switching, each switching device has only conduction loss and no switching loss, and the working efficiency of the circuit is greatly improved.
Because the input bus consists of C1 and C2 which are connected in series, when the capacitance values of the C1 and the C2 are unequal and have deviation, the voltages on the C1 and the C2 are not even, so that the voltage stress of part of the switching tube is increased, and the normal operation of the converter is affected.
The technical scheme provided by the embodiment of the application can solve the problem of unbalanced pressure of C1 and C2, and can automatically realize the voltage sharing of C1 and C2 by controlling the duty ratio of the switching tube through the controller without adding any hardware circuit, and the method is described in detail below with reference to the accompanying drawings.
And the controller is used for adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor so that the first voltage and the second voltage are consistent, namely C1 and C2 realize voltage sharing.
The controller is specifically configured to obtain a difference value between the first voltage and the second voltage when the first voltage is greater than the second voltage, and reduce a duty cycle of the fourth switching tube according to the difference value to increase the second voltage of the second capacitor; the duty cycle of the fourth switching tube is reduced by a positive correlation with the difference, i.e. the larger the difference is, the more the duty cycle of the fourth switching tube is reduced.
In specific implementation, voltages on C1 and C2 may be detected in real time or periodically, for example, the first voltage V1 on C1 and the second voltage V2 on C2, and the duty ratios of T1 and T4 may be adjusted according to whether V1 is greater than V2 or V1 is less than V2, so as to change the working mode.
The following first describes V1> V2:
And the controller specifically reduces the duty ratio of the fourth switch tube so as to increase the second voltage of the second capacitor.
See, for example, the driving timing chart when V1> V2 shown in fig. 5.
It can be seen from the figure that the duty ratio of T4 is reduced, that is, the duration of the high level of the driving signal corresponding to T4 is shortened, it should be noted that the high level corresponds to the on state of each pipe in the timing chart, and similarly, the low level corresponds to the off state of each pipe.
The duty ratio of the T4 is reduced, namely the T4 is controlled to be turned off in advance, so that the on time of the T4 is shortened, and the corresponding mode diagrams of the T4 on and the T4 off shown in fig. 6 and 7 can be seen.
When the duty ratio of T4 is reduced to a certain degree, T4 is turned off in advance when the resonance current is not yet 0, so that the current is changed from T4 to a D6 loop, and the charging of C2 is realized.
Fig. 6 corresponds to T4 being on, the current path at this time is: cr-Lr-T3-T4-C3-D8-Cr, i.e., cr and Lr charge C3.
Fig. 7 corresponds to the off T4, where the current path is: cr-Lr-T3-D6-C2-C3-D8, i.e., cr and Lr charge C2 and C3.
Because the voltage V2 on the C2 is lower, the C2 can be charged by controlling the T4 to be turned off in advance, so that the voltage V2 on the C2 is improved, the V2 approaches to the V1 and is finally equal to the V1, and the voltage equalizing between the C1 and the C2 is realized.
The following description describes V1< V2:
The controller is specifically configured to reduce a duty cycle of the first switching tube to reduce a second voltage of the second capacitor.
The controller is specifically configured to obtain a difference value between the first voltage and the second voltage when the first voltage is smaller than the second voltage, and reduce a duty ratio of the first switching tube according to the difference value so as to reduce the second voltage of the second capacitor; the amount of duty cycle variation is positively correlated with the difference, i.e. the larger the difference, the more the duty cycle of the first switching tube is reduced.
See, for example, the driving timing chart for V1< V2 shown in fig. 8.
It can be seen from the figure that the duty ratio of T1 is reduced, that is, the duration of the high level of the driving signal corresponding to T1 is shortened, it should be noted that the high level corresponds to the on state of each pipe in the timing chart, and similarly, the low level corresponds to the off state of each pipe.
The duty ratio of the T1 is reduced, namely the T1 is controlled to be turned off in advance, so that the on time of the T1 is shortened, and the specific reference can be made to the corresponding mode diagrams of the T1 on and the T1 off shown in fig. 9 and 10.
When the duty cycle of T1 is reduced to a certain degree, T1 starts to be turned off in advance when the resonance current does not drop to 0, and at the moment, the current is changed from T1 to a D5 loop, so that C2 is discharged.
Fig. 9 corresponds to T1 being on, the current path at this time being: C1-T1-T2-Lr-Cr-D7-C2, i.e., C1 and C2 charge Cr and Lr.
Fig. 10 corresponds to the off T1, where the current path is: C2-D5-T2-Lr-Cr-D7-C2, i.e., C2 charges Cr and Lr.
Because the voltage V2 on the C2 is higher, the C2 is discharged by controlling the T1 to be turned off in advance, the voltage V2 on the C2 is reduced, the V2 approaches to the V1, and finally the voltage is equal to the V1, so that the voltage equalizing between the C1 and the C2 is realized.
The above only describes in principle that the duty ratio of T1 and T4 is controlled and adjusted by the magnitude relation of V1 and V2, and since T1-T4 each have the maximum duty ratio, when T1 is reduced, since T4 is limited by the maximum duty ratio, the duty ratio of T4 cannot be increased any more, and can be kept unchanged. Ideally, the duty cycle of T1-T4 may be 50%, i.e. 0.5, but in actual operation there is dead time between the individual tubes, so the duty cycle is typically less than 50%.
The controller specifically adjusts the duty ratio according to the magnitude relation between V1 and V2, for example, the difference between V1 and V2 may be closed-loop controlled, so as to control the duty ratio of the driving signals output to T1 and T4, specifically, the duty ratio may be adjusted by proportional integral PI, proportional integral derivative PID, or other closed-loop controlled adjustment modes.
The following description will take the controller PI regulation as an example.
Referring specifically to fig. 11, a schematic diagram of a controller implementing control adjustment according to an embodiment of the present application is shown.
The controller is specifically configured to obtain a difference value between the first voltage and the second voltage, perform proportional integral adjustment or proportional integral differential adjustment on the difference value, obtain a duty cycle variation, respectively superimpose the variation on the duty cycle of the first switching tube and the duty cycle of the fourth switching tube, output the varied duty cycle of the first switching tube to the first switching tube after clipping, and output the varied duty cycle of the fourth switching tube to the fourth switching tube after clipping.
Since T1 and T4 each have a maximum duty ratio, it is necessary to clip the adjusted duty ratio and then output an actual driving signal.
Fig. 11 is presented by taking PI regulation as an example, and it can be seen from PI regulation shown in fig. 11 that the difference between the voltage of C1 and the voltage of C2, that is, V1-V2, is output by PI regulation, and d is superimposed on the original duty ratio of T1 and T4. When V2 is greater than V1, d is negative, so the T1 duty cycle is reduced, while T4 is limited by the maximum duty cycle, remaining unchanged. Conversely, when V1 is greater than V2, d is positive, so the T4 duty cycle is reduced, and T1 is limited by the maximum duty cycle, remaining unchanged.
According to the converter provided by the embodiment of the application, the duty ratios of the T1 and the T4 can be closed-loop adjusted according to the difference value of the voltages of the first capacitor and the second capacitor by comparing the voltages of the first capacitor and the second capacitor, so that the charge and discharge of the C1 and the C2 are controlled, the voltages of the C1 and the C2 are further adjusted, and the voltage equalizing of the C1 and the C2 is realized.
Based on the three-level resonant DCDC converter provided in the foregoing embodiment, the embodiment of the present application further provides a control method for the three-level resonant DCDC converter, which is described in detail below with reference to the accompanying drawings.
Referring to fig. 12, a flowchart of a control method of a three-level resonant DCDC converter according to the present application is shown.
The control method of the three-level resonant DCDC converter provided by the embodiment is applied to the converter described in the embodiment, and is realized by the controller in the embodiment.
The method comprises the following steps:
S1201: obtaining a first voltage of the first capacitor and a second voltage of the second capacitor;
s1202: and according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, adjusting the duty ratio of the first switch and the duty ratio of the fourth switch tube to enable the first voltage and the second voltage to be consistent.
According to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, the duty ratio of the first switch and the duty ratio of the fourth switch tube are adjusted, and the method specifically comprises the following steps:
When the first voltage is larger than the second voltage, obtaining a difference value between the first voltage and the second voltage, and reducing the duty ratio of the fourth switching tube according to the difference value so as to increase the second voltage of the second capacitor; the duty ratio variation of the fourth switching tube is positively correlated with the difference value.
According to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, the duty ratio of the first switch and the duty ratio of the fourth switch tube are adjusted, and the method specifically comprises the following steps:
When the first voltage is smaller than the second voltage, a difference value between the first voltage and the second voltage is obtained, and the duty ratio of the first switching tube is reduced according to the difference value so as to reduce the second voltage of the second capacitor; the duty ratio variation of the first switching tube is positively correlated with the difference value.
The specific implementation process of the control method of the converter provided by the embodiment of the application can be seen from the specific description of the controller in the embodiment of the converter, specifically, the duty ratios of the T1 and the T4 can be closed-loop adjusted according to the difference value of the first capacitor and the second capacitor by comparing the voltages of the first capacitor and the second capacitor, so that the charge and discharge of the C1 and the C2 are controlled, the voltages on the C1 and the C2 are further adjusted, and the voltage equalizing of the C1 and the C2 is realized.
Based on the converter and the control method provided by the embodiment, the embodiment of the application also provides a photovoltaic system, which comprises the converter introduced by the embodiment, a photovoltaic array and an inverter.
The input end of the DCDC converter is connected with the photovoltaic array, the output end of the DCDC converter is connected with the inverter, and the inverter is used for inverting the direct current output by the DCDC converter into alternating current and outputting the alternating current, so that the alternating current can be output to an alternating current power grid and also can be output to electric equipment.
It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
The above description is only of the preferred embodiment of the present application, and is not intended to limit the present application in any way. While the application has been described with reference to preferred embodiments, it is not intended to be limiting. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present application or modifications to equivalent embodiments using the methods and technical contents disclosed above, without departing from the scope of the technical solution of the present application. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present application still fall within the scope of the technical solution of the present application.

Claims (10)

1. A three-level resonant DCDC converter, comprising: the first switching tube, the second switching tube, the third switching tube, the fourth switching tube, the first capacitor, the second capacitor, the fifth switching module and the sixth switching module form a three-level DCDC circuit, and the first capacitor and the second capacitor are connected in series at the input end of the three-level resonant DCDC converter; further comprises: the device comprises a resonance capacitor, a resonance inductor, a first diode, a second diode, a third capacitor and a controller;
The first end and the second end of the first switching tube are respectively connected with the positive input end of the three-level resonance DCDC converter and the first end of the second switching tube, the second end of the second switching tube is connected with the first end of the third switching tube, the second end of the third switching tube is connected with the first end of the fourth switching tube, and the second end of the fourth switching tube is connected with the negative input end of the three-level resonance DCDC converter; the first end and the second end of the fifth switch module are respectively connected with the second end of the first switch tube and the first end of the sixth switch module, and the second end of the sixth switch module is connected with the first end of the fourth switch tube; the common end of the first capacitor and the second capacitor is connected with the second end of the fifth switch module; the positive output end of the three-level resonant DCDC converter is connected with the negative input end of the three-level resonant DCDC converter;
the third capacitor is connected in parallel between the positive output end and the negative output end of the three-level resonant DCDC converter; the first diode and the second diode are connected in series and then connected in parallel to two ends of the third capacitor;
The first end of the resonance capacitor and the resonance inductor which are connected in series is connected with the common end of the second switching tube and the common end of the third switching tube, and the second end of the resonance capacitor and the resonance inductor which are connected in series is connected with the common end of the first diode and the second diode;
The controller is used for adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor so that the first voltage and the second voltage are consistent.
2. The converter according to claim 1, wherein the controller is configured to decrease the duty cycle of the fourth switching tube to increase the second voltage of the second capacitor when the first voltage is greater than the second voltage.
3. The converter according to claim 2, wherein the controller is configured to obtain a difference between the first voltage and the second voltage when the first voltage is greater than the second voltage, and to decrease the duty cycle of the fourth switching tube according to the difference to increase the second voltage of the second capacitor; the duty ratio variation of the fourth switching tube is positively correlated with the difference value.
4. The converter according to claim 1, wherein the controller is configured to decrease the duty cycle of the first switching tube to decrease the second voltage of the second capacitor when the first voltage is smaller than the second capacitor.
5. The converter according to claim 4, wherein the controller is configured to obtain a difference between the first voltage and the second voltage when the first voltage is smaller than the second voltage, and to reduce the duty cycle of the first switching tube according to the difference to reduce the second voltage of the second capacitor; the duty ratio variation of the first switching tube is positively correlated with the difference value.
6. The converter according to any one of claims 1 to 5, wherein the controller is specifically configured to obtain a difference value between the first voltage and the second voltage, perform proportional integral adjustment or proportional integral differential adjustment on the difference value to obtain a duty cycle variation, respectively superimpose the variation on a duty cycle of the first switching tube and a duty cycle of the second switching tube, perform amplitude limiting on the varied duty cycle of the first switching tube, output the resultant amplitude limited duty cycle to the first switching tube, and perform amplitude limiting on the resultant duty cycle of the fourth switching tube, and output the resultant amplitude limited duty cycle to the fourth switching tube.
7. The converter according to any of claims 1-5, wherein the fifth switching module is a fifth diode, a cathode of the fifth diode being connected to a common terminal of the first switching tube and the second switching tube; the anode of the fifth diode is connected with the common end of the first capacitor and the second capacitor;
The sixth switch module is a sixth diode, the cathode of the sixth diode is connected with the anode of the fifth diode, and the anode of the sixth diode is connected with the common ends of the third switch tube and the fourth switch tube.
8. A method of equalizing voltage in a three-level resonant DCDC converter, applied to the converter of any one of claims 1 to 7, the method comprising:
Obtaining a first voltage of the first capacitor and a second voltage of the second capacitor;
and according to a comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, adjusting the duty ratio of the first switching tube and the duty ratio of the fourth switching tube to enable the first voltage to be consistent with the second voltage.
9. The method according to claim 8, wherein adjusting the duty cycle of the first switching tube and the duty cycle of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, comprises:
When the first voltage is larger than the second voltage, obtaining a difference value between the first voltage and the second voltage, and reducing the duty ratio of the fourth switching tube according to the difference value so as to increase the second voltage of the second capacitor; the duty ratio variation of the fourth switching tube is positively correlated with the difference value.
10. The method according to claim 9, wherein adjusting the duty cycle of the first switching tube and the duty cycle of the fourth switching tube according to the comparison result of the first voltage of the first capacitor and the second voltage of the second capacitor, comprises:
When the first voltage is smaller than the second voltage, a difference value between the first voltage and the second voltage is obtained, and the duty ratio of the first switching tube is reduced according to the difference value so as to reduce the second voltage of the second capacitor; the duty ratio variation of the first switching tube is positively correlated with the difference value.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101377121B1 (en) * 2012-12-28 2014-03-25 서울과학기술대학교 산학협력단 Non-isolated high step-up resonant converter
US9203321B1 (en) * 2013-03-04 2015-12-01 Universal Lighting Technologies, Inc. Non-isolated resonant DC-DC converter with boost-type voltage doubler output
CN106505866A (en) * 2016-12-02 2017-03-15 中国船舶重工集团公司第七〇九研究所 A kind of three Level Full Bridge DC converters
CN107231089A (en) * 2017-05-23 2017-10-03 中国农业大学 A kind of bidirectional three-level H bridges non-isolated dcdc converter
CN108400712A (en) * 2018-02-10 2018-08-14 杰华特微电子（杭州）有限公司 A kind of efficient reduction voltage circuit and its control method
KR20180105479A (en) * 2017-03-15 2018-09-28 전북대학교산학협력단 Soft-Switching Three-Level Bidirectional DC-DC Converter

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10014823B2 (en) * 2012-08-05 2018-07-03 Ben-Gurion University Of The Negev Research & Development Authority High efficiency resonant switched capacitor converter with continuous conversion ratio
US9350242B2 (en) * 2013-05-03 2016-05-24 Samsung Electronics Co., Ltd. Power supply and DC-DC converter with voltage drop circuit therein

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101377121B1 (en) * 2012-12-28 2014-03-25 서울과학기술대학교 산학협력단 Non-isolated high step-up resonant converter
US9203321B1 (en) * 2013-03-04 2015-12-01 Universal Lighting Technologies, Inc. Non-isolated resonant DC-DC converter with boost-type voltage doubler output
CN106505866A (en) * 2016-12-02 2017-03-15 中国船舶重工集团公司第七〇九研究所 A kind of three Level Full Bridge DC converters
KR20180105479A (en) * 2017-03-15 2018-09-28 전북대학교산학협력단 Soft-Switching Three-Level Bidirectional DC-DC Converter
CN107231089A (en) * 2017-05-23 2017-10-03 中国农业大学 A kind of bidirectional three-level H bridges non-isolated dcdc converter
CN108400712A (en) * 2018-02-10 2018-08-14 杰华特微电子（杭州）有限公司 A kind of efficient reduction voltage circuit and its control method

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